[Fundguy1]

I've heard from several people that diverter valves require periodic maintenance. I will need either diverters or a BOV. I'm trying to decide between the two. I want silent. I do not want to hear them at all. I don't even like to hear the whistle from my BMS DCI. So initially I ordered a VRSF charge pipe without the BOV bung. So if I was to switch to BOV I need to buy or exchange the charge pipe. Can someone tell me the maintenance necessary and how often to maintain diverters? I'm looking at forge. Otherwise is there a super super no noise at all BOV? Any pros or cons between the two besides maintenance? Thx

[C.Pop]

Maintenance is fairly simple; pick up a rebuild kit from Forge.

Generally when I unload an o-ring or seal, I replace it, but there were several times I disassembled the diverter valves, cleaned, and re-built with appropriate grease and didn't replace any of the O-rings/seals. The forge rebuild kit also includes new pistons, which won't need to be replaced until the existing ones are scored or marred in some way.

It wasn't hard to do the maintenance at all.

[Fundguy1]

How often does the maintenance need to be performed and how much are the parts, time to perform? I'm pretty tool savy. Can't rebuild a trans but with the exception of the internals of the engine, differential, and trans I've done a frame off restoration.

[max_k20]

From the info I read online when I was looking to purchase those i saw once a year for the maintenance (might want to clean/lube everything twice depending on boost level). THat's why personally I settled on the Tial BOV but IIRC from your other post you have a CP with OEM fitting so forge are pretty good but not set it and forget it.

[gtaccord]

I clean my forge dvs when I clean my dci filters which is once per year and that is while running 19 lbs of boost. They have never given me a problem otherwise. The maintenance aspect of the forge dvs is way overblown.

[Fundguy1]

Perfect. Thx guys

[Jklad]

I didn't clean my dvs until 45k miles after I bought them, they always worked fine. Evry 20k or 2 years should be fine. The kit is around $30, and it takes about 30 minutes to do. It's probobly the quietest option besides stock, but I removed my heat shield under the hood to make them sound louder and I think it's now perfect when combined with dci. I would recommend an er cp with forge DVs bc the vrsf one will cause them to touch or rub. I have a vrsf cp so i tried wedging some rubber grommets in between them do prevent metal to metal contact. The er cp has the dv bungs spaced out differently so you won't deal with this issue. It's not a big deal but just putting it out there. I have a post on here with some recommendations from helpful members on how to correct the spacing.

Ps. I've read about bovs that fail or stick on here, possibly due to oil blow by or something, so they may also need some level of 'servicing' or at least keeping an eye on them anyways. With dv you'll just be.more proactive.

[Dmacc]

I've rebuilt my forge DV's maybe 4 times now in 6,000 miles. I changed all o-rings, pistons, and greased everything accordingly. The diverters will be good for me for about 3 days after reinstalling, then they stick again. I'm losing my mind because it happens so often, I'm this close to selling the cp and diverters to go with a cp-e charge pipe and tial BOV. I'm running the yellow springs to make 14-15psi and they always leak under part throttle acceleration. I do not have any vacuum leaks, lines have all been changed, boost solenoids too. Holds 26hg at idle.

Anyone have any ideas of something I could try to fix this? It's the biggest pet-peeve I have about my car. The throttle is too laggy and makes driving stick perfectly almost impossible because I always bog at low rpm.

[ajsalida]

Originally Posted by Dmacc

I've rebuilt my forge DV's maybe 4 times now in 6,000 miles. I changed all o-rings, pistons, and greased everything accordingly. The diverters will be good for me for about 3 days after reinstalling, then they stick again. I'm losing my mind because it happens so often, I'm this close to selling the cp and diverters to go with a cp-e charge pipe and tial BOV. I'm running the yellow springs to make 14-15psi and they always leak under part throttle acceleration. I do not have any vacuum leaks, lines have all been changed, boost solenoids too. Holds 26hg at idle.

Anyone have any ideas of something I could try to fix this? It's the biggest pet-peeve I have about my car. The throttle is too laggy and makes driving stick perfectly almost impossible because I always bog at low rpm.

Are you sure they are installed the right way? Seems common that folks installed them backwards (I did at first too), and then they don't function as diverter valves anymore, they function as weak blow off valves with only the internal spring holding them closed, which is not they way they are intended to function. They should not open at all under any conditions under full boost, only when they get big vacuum when you let off the throttle abruptly to dump excess boost and avoid surge (hence the name, diverter and not BOV).

By backwards I mean there are two big hoses on each valve, if they are switched. You want the flat top of each valve facing each other, with the vac nipples pointing in towards the engine.

If you installed them correctly please ignore this comment.

[Dmacc]

Originally Posted by ajsalida

Are you sure they are installed the right way? Seems common that folks installed them backwards (I did at first too), and then they don't function as diverter valves anymore, they function as weak blow off valves with only the weak internal spring holding them closed. They should not open at all under any conditions under boost, only when they get big vacuum when you let off the throttle abruptly.

By backwards I mean there are two hoses on each valve, if they are switched. You want the flat top of each valve facing each other, with the vac nipples pointing in towards the engine.

If you installed them correctly please ignore this comment.

Unfortunately they're installed correctly I wish it were as easy as that. My connections to the chargepipe are as tight as can be and the vac line leading to the intake mani is also perfectly fine and secured as well.

What springs is everyone running? I've read on the other forum some are running the stiffer blue springs and aren't having any issues.

[C.Pop]

Mine required maintenance every few weeks to couple months tops before sticking would occur. I don't really consider that acceptable. The wide and varied input I got from people with them suggests that Forge may have a machining or tolerance stackup issue. Possibly it was just early revisions, Forge was always good to work with and willing to help, I just got tired of rebuilding them every few weeks.

[ajsalida]

I'm running yellow springs, no shims, no issues so far. Of course now I probably just jinxed them.

[Sgop335]

Originally Posted by Dmacc

I've rebuilt my forge DV's maybe 4 times now in 6,000 miles. I changed all o-rings, pistons, and greased everything accordingly. The diverters will be good for me for about 3 days after reinstalling, then they stick again. I'm losing my mind because it happens so often, I'm this close to selling the cp and diverters to go with a cp-e charge pipe and tial BOV. I'm running the yellow springs to make 14-15psi and they always leak under part throttle acceleration. I do not have any vacuum leaks, lines have all been changed, boost solenoids too. Holds 26hg at idle.

Anyone have any ideas of something I could try to fix this? It's the biggest pet-peeve I have about my car. The throttle is too laggy and makes driving stick perfectly almost impossible because I always bog at low rpm.

This is interesting and a little unexpected. How do you know the diverter valves stick? Do you have the means to pull them and check on a bench? Need air source to simulate charge pipe boost. A syringe connected to the nipple can be use to produce vacuum or boost.
I have hyperboost dvs. I checked them, when new, on a bench to compare with stock. It was an improvement, wish had the data. Its been many miles now perhaps i can check again.

[gtaccord]

I have used my set on two different cars with the yellow springs both times with absolutely no issues. To the people that have problems... each valve is made in 4 separate pieces. The nipple and the connection part to the cp can be unscrewed and separated. If these are loose this could be causing some of your problems. I accidentally unscrewed mine trying to install it one time. If they are loose they will leak.

Check this on both dvs and if loose, apply thread locker and retighten.

[C.Pop]

One of my jobs when I was working for the Department of Defense on nuclear submarine overhaul was valve work. Air, hydraulic, seawater, freshwater, you name it, I did it. Design, overhaul, maintenance, testing, all aspects. Nothing was overlooked, I was trying to be nice about it but Forge either sent me some early samples or needed to beef up their QC a bit.

Again, I had friends that have had no problems whatsoever for years on the valves. It doesn't mean that my problems weren't real. Just means some guys got luckier than others and most likely there is an unfavorable tolerance stack that can happen from time to time. The forge I used on my Subaru before the BMW was perfect. *shrug*

[ajsalida]

Just in case anyone did not get the instructions from Forge, one possible reason seals may not be holding or getting damaged often is due to not following the note on the last page about re-assembly:

BEFORE you attempt to screw the bottom port back onto the body, you MUST compress the piston in the
valve body and secure it there with your finger over the vacuum nipple to hold it in place. Failure to do so
may cause damage to the o-rings inside the body.
Very carefully press the piston all the way into the valve body far enough that you can see the threads for the
bottom port through the side port of the valve. This may take some careful rocking of the piston side to side
to ensure it seals against both internal o-rings. Once the threads are visible through the side port, use your
finger to cover the vacuum nipple to hold the piston in place while you use your other hand to screw the
bottom port back into place.
You may also use a vacuum pump if you have one available to you to hold the piston in place while securing
the bottom of the valve. See the photo below for reference.

see last page of PDF attachement for picture and compete install instructions:

[Dmacc]

Yes, I always compress the piston and hold my finger over the vacuum port to ensure there is no o-ring damage taking place when re-screwing them back together.

I've also made sure in the past that the vacuum nipple was secured properly and didn't leak by applying lock-tight to those threads as well.

It sounds to me like I may have received a faulty set judging by the responses in the thread. I'll give Forge a call today and will see what they say.

[Ilma]

Originally Posted by Dmacc

Yes, I always compress the piston and hold my finger over the vacuum port to ensure there is no o-ring damage taking place when re-screwing them back together.

I've also made sure in the past that the vacuum nipple was secured properly and didn't leak by applying lock-tight to those threads as well.

It sounds to me like I may have received a faulty set judging by the responses in the thread. I'll give Forge a call today and will see what they say.

You may not have a leak at all........

The diverter valves are designed to crack open when there is a 4+ psi difference between boost pressure in the chargepipe and boost pressure in the intake manifold.

The pressure in the intake manifold is transmitted via the vacuum line from the diverter valves you tap into.

If you are WOT then pressure in the chargepipe and the manifold are the same and there is equal pressure on both sides of the diverter piston keeping it in it's default closed position.

But at part throttle you can build boost in the chargepipe much faster than it gets into the intake manifold simply because a partially open throttle plate is resticting air flow........if that differential pressure is more than 4psi then your diverter valves will hiss and bleed pressure.....even at parial throttle openings.

Mine do this all the time at part throttle settings and I can audibly hear them hissing. As soon as I get deeper into the throttle the hiss disappears until I shift gears.

Is it the hissing sound at part throttle that makes you think you have leaking diverters?

[Sgop335]

Heres data I have on hyperboost dv...Tomorrow, will add stock values.

Charge pressure (boost) manifold pressure to keep valve closed
<= 6psi ........... 0
7psi ............ 1.5
8 ............ 3
9 ............. 4
10 .............. 5

Good to see a differential of 5 - 6 psi!

[Dmacc]

Originally Posted by Ilma

You may not have a leak at all........

The diverter valves are designed to crack open when there is a 4+ psi difference between boost pressure in the chargepipe and boost pressure in the intake manifold.

The pressure in the intake manifold is transmitted via the vacuum line from the diverter valves you tap into.

If you are WOT then pressure in the chargepipe and the manifold are the same and there is equal pressure on both sides of the diverter piston keeping it in it's default closed position.

But at part throttle you can build boost in the chargepipe much faster than it gets into the intake manifold simply because a partially open throttle plate is resticting air flow........if that differential pressure is more than 4psi then your diverter valves will hiss and bleed pressure.....even at parial throttle openings.

Mine do this all the time at part throttle settings and I can audibly hear them hissing. As soon as I get deeper into the throttle the hiss disappears until I shift gears.

Is it the hissing sound at part throttle that makes you think you have leaking diverters?

Thank you for the reply! The hissing at part throttle is what I'm talking about, yes. Each time I rebuild them, that part throttle hissing isn't there. In turn, my throttle pedal is much more crisp and I don't have any low end bog. This typically lasts 3-4 days, before they start to hiss again at part throttle and the bog returns. Would switching springs or adding a shim make any difference? I appreciate the help!

[ajsalida]

Originally Posted by Dmacc

Thank you for the reply! The hissing at part throttle is what I'm talking about, yes. Each time I rebuild them, that part throttle hissing isn't there. In turn, my throttle pedal is much more crisp and I don't have any low end bog. This typically lasts 3-4 days, before they start to hiss again at part throttle and the bog returns. Would switching springs or adding a shim make any difference? I appreciate the help!

This is a really interesting discussion and has caused me to realize I don't fully understand how these valves work. Anybody, please feel free to chime in here and correct me.

I think they are supposed to be open at idle and other high vacuum situations not under boost. Then as boost builds in the charge pipe and pressure equalizes inside the intake manifold (or crosses some press. diff threshold), they close. When you lift off the throttle and vac or pressure differential builds between CP and intake, they open again.

However if they are sticky they won't close fast enough under building boost (lag + more noise) or open soon enough after letting off throttle (boost spikes). The former seems to square with what you are seeing after the rebuild "wears off".

What I don't understand here is why they would be designed to open at such small pressure differential (4 psi), it would seem that would interfere with spool up and throttle response esp at part throttle. I think maybe it is a trade-off between taking longer to close moving from closed throttle to open, vs staying closed too long while under boost and moving to part throttle.

I guess you could calculate the pressure differential at which they are supposed to crack open, and then by how much. Effective piston area x PSI diff > spring force @ closed position. Or just measure it with a vac pump and gauge.

If throttle response is deteriorating and feels laggy maybe they are just sticking open. And similarly if logs are showing bigger than desired boost spikes on closure, they are sticking closed. Seems to me a properly working valve should not bleed off too much boost to feel laggy, or at least it is not closing fast enough if it is interfering with response like that. And maybe it makes more noise that sounds like a leak at part throttle.

Now I need to take mine apart because I have been getting some intermittent long spool up times esp from fully closed to WOT throttle and inaccurate boost tracking vs target on logs, I had figured it was sticky wastegates but it might just be sticky DV's. Also the grease Forge specifies is Mobil 1 bearing grease, so that may be a factor. I figure very cold weather might be an issue too until inside the engine compartment seals grease etc. warms up.

[Ilma]

Originally Posted by Dmacc

Thank you for the reply! The hissing at part throttle is what I'm talking about, yes. Each time I rebuild them, that part throttle hissing isn't there. In turn, my throttle pedal is much more crisp and I don't have any low end bog. This typically lasts 3-4 days, before they start to hiss again at part throttle and the bog returns. Would switching springs or adding a shim make any difference? I appreciate the help!

I can confirm that I don't always get the hissing......and acceleration is more noticeable.......depends upon the throttle opening and there are just so many possible combinations of part throttle/rpm.

I started digging deeper and logging my CAN DBW throttle opening versus pedal angle and what I found is that sometimes even though my throttle pedal is depressed paritally the DBW throttle plate seems to stay shut for a second or two and then suddenly catches up and creates a small jerk in acceleration.

Feels just like a sticking throttle plate....but the DME is not throwing any codes related to incorrect throttle plate angles, so I am wondering if it is a low rpm tuning issue related to torque management

I run a custom backend flash for timing, AFR and load, but the torque management tables are still pretty much stock values.

Point is that I can see on my datalog that the DBW throttle plate is not opening at the correct time and causing a restriction as boost is building in the chargepipe.......this would explain why the diverter valves are bleeding pressure.

So in my case I don't think it is the diverter valves that are sticking....but rather my throttle plate behaviour forcing them to crack open at certain part throttle settings where I build boost but the throttle plate stays shut momentarily.

It only happens at certain throttle angles and not if I push the throttle a little more aggresively......so that is why I suspect it is tuning related rather than mechanical. A steeper throttle angle probably puts me in a different spot on the torque management tables.

In a properly tuned setup I would expect that the CAN DBW throttle plate is always ahead of the throttle pedal angle so that there is no restriction in the way of boost.

You may want to consider logging your throttle data as I suspect this hissing at part throttle may be more of a symptom rather than the actual source of the problem